Solid oxide fuel cells (SOFCs) can generate power in the range of 1-100 kW power with an efficiency of 60-70%. SOFCs can be operated using different fuels like alcohol, hydrocarbons ammonia and gases like methane. Thus, fuel flexibility is one of the important advantages of SOFCs over other fuel cells.
The SOFCs are currently operated in the temperature range of 800-1000° C., restricting their application in stationary power generators. The operating temperature of SOFCs must be reduced to the range of 400-600° C. to extend the use of SOFCs to automobile and other applications. Ionic conducting electrolytes can be utilized to reduce the operating temperature range of SOFCs. Yttrium stabilized zirconia (YSZ) has an oxygen conductivity of 0.1 S/cm above 800° C. Doped ceria, lanthanum gallate and lanthanum manganite based electrolytes have ionic conductivity comparable to YSZ in the operating temperature range of 700-800° C.
Further, electrolytes doped with carbonate salts like sodium carbonate, potassium carbonate, barium carbonate and strontium carbonate either alone or in combination have low ionic conductivity in the temperature range of 400-600° C. However, these carbonate doped electrolytes are chemically unstable and are less durable than ceramic electrolytes. Also, the higher operating temperatures of SOFCs create problems in sealing of the SOFCs.
Therefore, there is felt a need to provide a stable electrolyte which can provide better ionic conductivity at a lower temperature.